Investigation of deep levels in rapid thermally annealed SiO2-capped n-GaAs grown by metal-organic chemical vapor deposition

Defects created in rapid thermally annealed (RTA) SiO2-capped epitaxial GaAs layers grown by metal-organic chemical vapor deposition have been investigated by deep level transient spectroscopy. RTA introduced four electron traps S1 (E-c - 0.23 eV), S2 (E-c - 0.46 eV), S3 (E-c - 0.72 eV), and S4 (E-c - 0.74 eV). S1 may be the so-called EL9 defect. We propose that S2 is a defect complex involving the Ga vacancy and Si dopant atoms, V-Ga-Si-Ga, and associate it with the EL5. S2 is introduced almost uniformly within the first 0.8 mu m below the surface with an activation energy of 4.4 eV. S4 is most probably one of the EL2 family. The concentration of S4 decreased exponentially below the surface with a characteristic decay length similar to 0.2 mu m. The activation energy for the introduction of S4 is 2.5 eV. (C) 2000 American Institute of Physics. [S0003-6951(00)01931-8].